Testing hammer rock drill



Mach 9 ,1926. 1,576,465

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March 9 ,1926.

L.. PRYCE TESTING amsn Rocx DRILL v Fued oqt. 5. 192s 2 sheets-sheet 2 H9511 tor 3 Patented Mar. 9, 1926.

UNITED STAT-ES PATENT ortica.

TESTING HAMMER ROCK DRILL.

Application filed October 5,1923. Serial No. 666,826.

To all 107mm t may concern.'

Be it known that I, Lnsmn Peron, engineer, British subject, residing' at Corner I-Iouse, Commissioner Street, Johannesburg, Transvaal, Union ot South Africa, have invented certain new and useful Improvements in Testing IIammer Rock Drills, of which the following is a specification.

The `present invention has reference to hammer rock drills and particularly to such drills in which .the rotational movement of the chuck is positive withl the reciprocatory movement of the piston. The purpose of the invention is to enable a short period test ot' such drills to be made in a fitting shop or testing room, which gives a practical measure ot their fitness for actual drilling. v

Accordingly the drill is run with standard air pressure and under a standard load which approximates in kind and amount. to the normal working load, and the speed of movement is measured. In a hammer drill in which the tool rotation and the piston reciprocation are positive with one another, the rotational power of the drill furnishes a reliable index of the working capacity o the drill; andaccordingly in carrying out the invention in the preferred manner, with this type of drill, the load from which the measurement is derived is arranged to resist the rotational movement, and the speed ojl rotation under t-heload is measured. y l y y A testing apparatus according to the invention is illustrated inthe accompanying` drawings ln which- Fig. I is a side elevation, showing the drill in position 'for test.

Fig. II is a cross section on line II, II ot Fig. I, seen 'from the 'direction et the arrow A, the drill being removed. Fig. III is a longitudinal section of the testing block, drawn to an enlarged scale.

2 indicates a table on which acradle 3 is :tree to slide. Thecradle is provided with lugs 4 in which are removably [secured mountings 5 adapted to carry the kind of drill under test.

The drill shownis of a well known construction comprising a `cylinder 6 and a loose hammer piston 7 reciprocating therein. rThe piston is provided with a forward extension 8 which strikes the drill. YThe pistonl is rotated by a rifle bar 9 and in turn rotates the tool chuck 'l0 and the tool 21 therein by means ot' interenga'ging flutes 1l, on the extension and the chuck.

rlthe cradle 3 is pressed towards the testing` block lf2 by means exerting a constant force, suchv as the weight 13 hanging from a chain l-l which passes over a lixed pulley 15 and is connected to the cradle through atension spring 16. The latter prevents the rapid vibrations which are set up in the cradle trom being' transmitted to the weight 13. Y i

vFor holding the cradle' from its operati vc position, there is provided a lever 17 operating; an arm 18 which can engage the :trent '7 end' of the cradle. When the lever is fully retracted,- the arm 18 engages in a notch 19 in the cradle and so locks the parts in the retracted position. lYVhen in its torward position the arm 18 lies against a stop Q0.

the regular drilling tool -or the hammer drill under test, except that it has a llat end 22 and 4isi-usually shorter than the regular drill tool. It is shanked at 23 as may beV necessary, similarly tothe regular tool, to receive the blows of the hammer piston 7 and to receive rotary motion from the tool chuck 10, I

The testingl block :l2 comprises resilient meansktor resisting' the limpacts ot the tool 21, constantly loaded rotary means, rotated by said tool, and means :lor n'ieasuring the angular speed ot said rotary means.

In the form shownit consists ot' a cylin-` drical `easing' 2.4 provided with a toot bolted to the table Q. -Ar cylinder 26 is rotatably mounted within the casing; the internal surface ol the -casing and the external surtace o't the cylinder preli'erably being' polished` to insure uniform bearing` friction between them. Loosely inserted in Athe bore 27 of the cylinder is a hard steel disc 28 against which the tool 2l presses. Said dise is resiliently supported by a number ot' rubber blocks 29 accommodated in the bore 27. r

lIhe endwise lthrust of the cylinder 2G is taken up by arthrust bearing consisting' oit a 'flange 3U on the cylinder 2G, a similar flange 3l on the casing` 24 and a loose brass washer 32 interposed between them. The

21 indicates a tool which is similar to f frictional surfaces between the casing 24 and the cylinder' 26 may be lubricated by oil introduced through the hole 33. On the liang'e 30 is fixed a plate 34 formed with a non-circular hole 35, into which is en- ,Qagged the similarly sectioned end of the tool `21,whereby rotation of the latter is imparted to the cylinder.

36 is a belt pulley fixed to the cylinder 26 and drivin; a revolution indicator 37. The pulley is shown as bearing on the end 38 of the casing` 24, in order to keep the thrust bearing' elements 30, 3l, 32 in contact. rihe rotational impulses from the drill being' intermittent, it is desirable in order to obtain a regular indicator reading, to regulate the rotation of the cylinder Q6 by means of a fly wheel 39.

Compressed air from a source 40 is supplied to actuate the drill under test, through a. reducing valve ell, which ensures the maintenance of a uniform and standard pressure.

In makina' a test, the. drill (i vis mounted on the cradle 3, the tool 2l. placed in the drill chuck l0 and the lever 17 thrown forward, so allowing the weight 13 to pressthe cradle, with a standard pressure, towards the test block l2; this pressure being' transmitted through the tool 2l to the disc 2S and thrust bearing 30, 8l, 3Q. Air is then turned on to operate the drill. The rebound of the tool 2l from the disc 28 and the rebound of the hammer piston from the tool, approxi mate to those which occur in actual drilling` sufficiently for the purpose of the test, and it is found that a very rough approximation is all that is necessary. The. "otation of the tool chuck 10 is transmitted by the tool 2l to the cylinder Q6 and is resisted by the general frictional resistance of the cylinder in the casing' 24 but more particularly by that of the thrust bearing 30, Sl. 32; these being' found to provide sufficient resistance without the use of a special brake. The rat-c of rotation as indicated b v the indicator 37 is noted and is taken as a measure of the drills performance.

.Tn practice a drill of a certain design and in a standard condition of fitness is first. tested and the reading' ot' the indicator 23T is noted. This is taken as the standard for that make; and a co111pari. m of the reading of another drill of the same make with such standard reading` provides a reliable measure of the fitness of the second drill for its intended work.

l claim:

l. The process of testing a hammer rock drill in which the reciprocating' movement Vof the piston and the rotative movement of the tool chuck are posit-ive with one another, which consists in running' the drill by means of working fluid at standard pressure and under a standard rotational load and measuring` the angular speed of the chuck.

2. The process of testing` a hammer rock drill in which the reciprocating movement of the piston and the rotative movement of -the tool chuck are positive with one another, which consists in establishing a standard by running a standard drill by means of Working` fluid at standard pressure, and under a standard rotational load, ineasuringtlie angular speed of the chuck, running another drill of the same make under the same conditions, and comparing the rotational speeds thus obtained.

3. A hammer drill testing machine, comprising' means adapted to receive the impacts of the hammer piston and to offer a constant resistance to such impacts, means adapted for rotation under constant load conditions and further adapted to be rotated from the tool chuck of a hammer rock drill, and devices for measuring' the angular speed of said means.

fl. A hammer drill testing machine, comprising means adapted for rotation under constant load conditions and further adapted to be rotated from the tool chuck of a, hammer drill, devices' for ieasurinn the angular speed of said means, and a resilient impact means` adapted to receive the impact of a tool mountedl in the hammer drill and to offer a constant resistance to such impact.

5. A hammer drill testing machine comprising a movable mounting for the drill, a testingblock comprisiin` means for resiliently resisting with constant resistance the impact-s of a tool mounted in the drill. means for urging rthe drill mounting toward the testing' block, rotary means adapted for rotation under constant load conditions and further adapted to be rotated by said tool. and devices for measuring the angular speed of said rotary means.

6. In a hammer drill testing' machine, a testing' block comprising,` a casing', a cylinder rotatable therein, a thrust bearing between the cylinder and the casina', the cylinder being constructed to be engaged by the tool of a hammer drill for rota,- tion therewith, and means for measuring the angular speed of the cylinder.

T. ln a hammer drill teg-tine' machine. a testing block comprising'a casing'. a cylinder rotatable therein, means in the cylinder' for resiliently receiving' the impacts of the tool of a. hammer drill, a thrust bearing between the cylinder and the casing, the cylinder being' constructed to be engaged by said tool for rotation thereith, and means for measuring' the angular' speed of the cylinder.

S. Vln a hammer drill testing machine. a testing block comprising` a. casing, rotarv means rotatably supported therein and adapted to be rotated from the tool chuck of lll() a hammer drill, means to exert constant re sistance to the rotation of said rotary means, a fly wheel regulating the rotation of said rotary means, and means on said rotary means for driving a revolution indicator.

9. In al hammer drill testing machine, a rotatable vmember adapted to` be rotated by a hammerl drill tool, means to exert constant resistance to the rotation of said member, and an impact piece mcvably mounted and resiliently supported in said member and adapted to receive the impacts o the tool.

10. In a hammer drill testing machine, a casing, a cylinder rotatable therein, a thrust bearing between the cylinder and the casing, means at the end of the cylinder forming a socket for insertion of a tool and providing rotational engagement between the tool and the cylinder, means 1n the cylinder for recelvmg the impacts of the tool, and means Aprising a table, a cradle slidahly mounted thereon and adapted for Vmounting hammer drills, a testing block comprising a casing.

mounted on the table and formed withan internal bore, a. cylinder rotatable in the bore, a thrust bearing between the cylinder and the casing, the front oi the casing being constructed for receiving and rotatably engaging a tool, resilient impact receiving means in the cylinder engageable by such tool, a {iy wheel on the cylinder,1neans on the cylinder for driving a revolution indicator, Vand a constant pressure device for urging the cradle toward the testing block.

In testimony whereof I have hereto appended my signature.

LESLIE PRYCE. 

